A system-on-a-chip (SoC) is an integrated circuit (IC) that integrates many or all components of a computer or other electronic system into a single chip. A typical SoC comprises many functional units, which may include microprocessors, memory blocks, timing sources, peripherals such as counter-timers, and external interfaces such as a Universal Serial Bus (USB) port and an Ethernet port. Each functional unit requires configuration access and debug access in order to enable its operation. During various phases of a design cycle, different functional units may be added, dropped, or relocated. As a consequence, the configuration scheme can become complicated and delicate, and often requires the involvement of the entire design team.